On 7/29/2015 11:56 AM, Wayne wrote:


"John S" wrote in message ...

On 7/28/2015 12:58 PM, Wayne wrote:

"John S" wrote in message ...

Hey, Wayne -

Do you have or want EZNEC? There is a free (limited) version.

Just curious.

Thanks. I have version 3.0, and it does the job for me.

I got my first copy back in the days when W7EL frequented this group and
knew by call sign who had legal copies

The hidden reason I asked the question is that I think you should
model some antennas and look at the current on the shield of the
transmission line. I have done this, and I don't see major problems if
the system remains balanced just as lore suggests.

This brings up a question of my own. By changing the slope of the coax
shield, I can get increased current in it. The question is, at what
point does it become a problem? As far as the antenna pattern is
concerned, I would not worry. RF in the shack is another matter. In
about 1958, my lips got some RF when they touched the D104 mike.
Didn't hurt me, but I didn't like it. At the time I had no
understanding of this phenomenon.

Anyway, it would be nice if we could decide, measure, or simulate how
much feed line current should be allowed. Maybe the answer is to
simulate how much voltage appears in the shack.

Lots of questions. A large area for investigation.

The reason for my balun question (other than to generate meaningful
technical banter on the newsgroup) is that some years ago in the age of
sliderules, a widely known and respected antenna guru told me that a
balun was unnecessary at resonance ( j=0 ).

I lost touch with him and don't know if his views changed over the years.

I disagree with him.

Please see Roy Lewallen's (W7EL, author of EZNEC) site for some good
reading. He is a superb writer of easy to understand technical tidbits.
He has some balun stuff among other stuff.

http://eznec.com/misc/